Propellant propulsion system for helicopters



R. J. GEHRKE Feb. 16, 1960 PROPELLANT PRoPULsIoN SYSTEM FOR HELICOPTERS Y Filed Deo. 29, 1954 M M W W W M United States Patent i O.

PROPELLANT PROPULSION SYSTEM FOR HELICOPTERS Richard J. Gehrke, Chatham, NJ., assignor, by mesne assignments, to Thiokol Chemical Corporation, a corporation of Delaware v i Application December Z9, 1954, Serial No. 478,350

2 Claims. (Cl. 60-39.35)

l The present invention relates to propellant feed systems for helicopters of the type wherein the airfoil rotors are driven by small reaction-type propulsive units mounted exteriorly of the aircraft fuselages for revolution with the airfoil rotors about their rotational axes.

In a helicopter of this type, numerous structural and operational problems are involved in delivering the liquidv propellant from a fuselage-carried supply tank through the central rotor column and hub outward to the whirling propulsive units in an ecient and reliable manner. The delivery conduit must be leakproof; the delivery rate must be adequate to meet consumption requirements; and,

since the present trend is toward simplicity and lightness sent leaky joints which would reduce the economy ofpropellant supply and might even become ahazard when certain kinds of propellants are used.

Another object is to provide improved and extremely simplified propellant pumping means which utilizes the unitary conduit structure as means by which driving power may be transmitted directly from the propulsive units to the pumping means, whereby the propellant will be delivered at a volumetric rate directly proportionate to the rotational velocity of the rotor.

A further object is to provide a propellant feed system wherein the means for forcing the propellant from the supply tank through the delivery conduit .to the propulsive units cooperatively combines sequentially applied component forces to include the initial effect of a pressurized supply tank, the secondary effect of positively driven pumping means, and the final elect of centrifugal force generated by the airfoil rotor.

vOther objects, advantages and features of the invention will become apparent as the following specific description is read in connection with the accompanying drawing, in which:

Figure 1 is a fragmentary elevational View, partly in section, of one embodiment of the improved feed system installed in a helicopter;

Figure 2 is a similai` view of a modification of the same; and,

Fig. 3 is a fragmentary plan view of one of the propu1- propellant 2,924,936 Patented Feb. 16, 1960 ICC . adapted for use with either of these alternative modes of mounting and propulsive units and either application is to be understood to be within the spirit of the present invention. Moreover, the system is capable of serving propulsive units of any reaction type, such -as ramjet engines and rockets, and any such use is also embraced within the spirit of the invention.

Before referring in detail to the accompanying drawing, it may be explained that representation therein of those parts of the helicopter most closely associated with the new propellant feed system is relatively diagrammatic and fragmentary in order not to confuse structural features of the claimed invention with conventional aircraft structure. For instance, the outline of one airfoil blade is traced in dot-and-dash lines merely to indicate the general arrangement of the radial branch conduits of the propellant feed System inside the rotor blades as contemplated when the propulsive units for the respective blades are tip-mounted. All other conventional operational parts or mechanisms ordinarily applied to the blade roots, such as means for cyclic pitch change and the like, have been omitted from the disclosure because they are only necessarily incidental to the present invention and are not claimed as essential elements thereof.

Referring now to the embodiment of the invention disclosed in Figure l, it will be observed that the propellant feed system includes as its basic structural element the vertically extending tubular housing 1l) which is joined rigidly and securely as by Welding or other suiciently Strong means, to the airframe of the helicopter indicated at A. The reason why a strong joint is important-is that housing 10 very likely will have to support the entire weight of the aircraft and its load from the lifting rotor. In other words, housing 10 may constitute the mast which serves as rotary mounting means for the airfoil rotor column or shaft, which, in accordance with the present invention, is made tubular in construction in order that it may be utilized as the main conduit section of the proposednew propellant feed system. This shaft, which is designated by the numeral 11, is rotatably mounted coaxially within housing 10 and preferably is sufficiently smaller in diameter than the latter to provide an annular space 12 therebetween of predetermined radial extent for a particular purpose to be described presently. Any suitable means for rotatable mounting of shaft 11 within housing 10 may be employed, but the upper and lower annular bearings 13 and 14 located in the upper region of space 12 have been Vchosen for purposes of convenient illustration. I

The upper end portion of shaft 11 is shown as protruding from housing 10 and provided at its `extremity with a pair of diametrically aligned tubular arms 15-15 formed integral therewith. 'The number of arms obviously will conform to the number of airfoil rotor blades B when the propulsive units C are tip-mounted, but may be of any selected number when units C are independently mounted. In either adaptation, arms 15-15 are communicably connected to the hollow interior of shaft 11 at their inner ends and to the propulsive units C at their outer ends in order that these arms may function as.`

branch propellant conduits. At the juncture of arms @new 15e-.15 with shaft 11, an upwardly diverging'deector i formation 15a has been provided inside. shaftk 1.1 in closing relation to its upper extremity to divide the propellant stream and to direct its branches into the respective branch conduits.

Arms 15-15 are shown as being extended radially outward through blades B from the roots thereof to the tip-mounted fuel-consuming propulsive units C, to the propellant intakes of which they are communicably connected in any conventional manner. It is to be understood that under some circumstances it may be desirable to make the outer end portions ofv arms 15--15 ilexible. instead of rigid, as presently shown. Obviously, when the propulsive units are independent of direct supported connection with the rotor blades, arms 15-15 will be.

friction thrust bearing 17, which may be of. any desiredl type. v

The lower portion of housing 10, which is. located within airframe A, is sealed hermetically in Vpenetrating relation to the top wall of a propellant supplyA tank` 18 and has its open lower end extending to a'position in close proximity to the bottom of the tank in order that it will be immersed at all times in any propellant contents.

D thereof.

The lower end portion ofspace 12, `which, intervenesy between the opposed inner and outer peripheral surfaces of housing and shaft 11, is utilized as a workingy chamber 19 for` propellant pumping means` 20. This pumping means. preferably is in the form of1 a lifting screw aflixed to, or otherwise made rigid with, shaft. 11

The direction of helical twist of the screw should be soy related to the normal direction of rotationk of shaft 11 caused by operation of rotor, blades B that propellant liquid entering the lower end ofrhousingl 10- willbe drawn upward into the latter. ImmediatelyI above pumping screw 20, plural port openings 21k are provided in the wall of shaft 11 to permit flow of propellant from working chamber 19 into the interior of the shaft.. In order to seal space 12 immediately above openings 21 and thereby resist undesired flow of propellant in by-passing relation to the upper region of the main conduit afforded by shaft 1i, a stuffing box conventionally represented at 2 2 is provided. Because slight leakage through stufng box 22 may occur with wear, a drain duct 23 has beeny provided to lead from space 12 immediately above the. stuffing box back into the top of tank. 18. To permitthe drain duct to be shut off while pressurizing tank 18 under operational conditions to be described later`r herein, the.

former is controlled by valve means 24. As shown. in Figure l, a pressure line 25 leading from any convenient source of compressed gas (not shown) is connected with the interior of tank 1S at the top thereof. Valve means 2,6 is provided in pressure line 25 to permit control and.

shaft 11 and outward through theV branch conduits of. arms -15 to the respective propulsive4 units. There-.-`

yafter, when shaft 11 is rotating under the drivingA power of the propulsive units, pumping screw. 2.0v will force.i the propellant upward through the main conduit in shaft 11.

until its stream reaches the'` level of arms 15-,15`anllis1 divided by Vdeflectorl 15a into lateral branchv streams'iiow i ing radially outward into tht-:branch conduits formed byY armslS-li Under the influence ofi centrifugalforce.

A generated by revolution of propulsive units C'and arms 15-'-15, further progressil of the propellant will bek motivated within the branch conduits. Itshould be apparent that the feeding of propellant to the propulsive units will be at a volumetric rate directly proportionate to the rotational velocity of the airfoil rotor, which should insure a constantly adequate supply to meet con sumption requirements. Moreover, with a unitary structure of main and branch conduits such as has been devised, the possibility of leakage at any point between the supply tank and the propulsive units is very remote.

The structure of the modified form of feed system disclosed in Figure 2 differsl from that of Figure l in the shortening ofqh'ousingltl to bring it entirely within the interior of ai'rframe'A'v andin the lowering'of hub 16' on shaft 11 into contact with, and attachment to, the

airframe. Withthis change, the weight of the airfrarfne A and V its loadwill be supportedby shaft 11T through antifriction thrust bearing 17.. An advantage of this inodiiication is toV reduce the. over-all weight ofV the; construction, which is particularly desirable when arms 15'-15 become power arms for direct ysupport of propulsive units independent of rotor blades B'. Similar to the details of construction disclosed in Figure l, a deector formation 15b islocated at the upper end ofthe main conduit. The lower end of shaft 11y is journaled'in asingle bearingn 13y in housing 10 and pumping screw 20' isaixed to its-lowerend portion within working chamber 19', which latter is dividedffrom'the superposed portion ofl space 12'l by sealing-means-in` the form of stuiiing box'22. They top wall of supply tank 13 is connected by drain duct 23V to( space 12 immediately above stuffing box 22 and isv controlled. by valve means 24.. Openings 2.1v provide communication between Working chamberA 19 and theinterior` off the mainY propellantl conduit constituted byshaft 11. controlledby valve means 26.

While a helical pumping screw is disclosed herein as a preferred embodiment of.v the invention, a centrifugall impellenor other rotary type of. pump could be employed withoutdeparting from the spirit oftheinvention.

While `there have been shown anddescribed and pointed out the fund-amentalnovel featuresof this invention as applied.' to. only. two physical embodiments, it will beV understoodV that'various omissions and 'substitutions andv changes. in the form anddetails ofthe device illustrated and in its operationmay be made. by those skilled. in.

theart without departing fromthe spirit. of theinvention. It is -the intention, therefore, to befliinitedv only,l as.

indicated.l by the scope of the following claims.

- What is claimed is:

l. A fuel feedingl system for delivering fpel from a supply, tank toa plurality of propulsion units for com-v bustion therein to effect' rotation ofthe units about a,

vertical axiscomprising a stationary tubular housing concentric-with the" axis and having` a sealed connection with and extending intoy the. tank` to, a point adjacent they bottom thereof, a unitary f uel conduit rotatably mounted4 coextensively and'coaxiallywith and withinV saidhousing openings formed in saidV fuel conduit below said sealingl means to afford communication between said housing and" said' rotating fuel conduit for fuel owinto the latter, and rotary pumping means coextensive with and,`

xed to the rotatable fuel-conduit below *said` ports to pump fuel from the tank through *saidfhousing and said ports into said rotatable fuel conduit Iand through integral branch conduits tothe propulsion units-for corri:-l

bustion therein upon rotation of saidfuel conduit.i

. 2.-. The. investitataed-i'siainifWltteafhal Tank 18' isprovidedwith pressure lineZSf-A ing means for the rotating fuel conduit is in the form of a screw axed to said conduit for rotation therewith.

References Cited in the file of this patent UNITED STATES PATENTS Avigdor Nov. 25, 1941 6 Palm -2---- Nov. 14, 1944 Gerhardt Mar. 20, 1945 Piccardo et al. July 22, 1947 Mayer July 27, 1948 Margolis May 30, 1950 Wilson Mar. 13, 1951 Kerry Oct. 5, 1954 Sforza Del Pesaro June 7, 1955 FOREIGN PATENTS Italy Mar. 4, 1953 

